PROJECT DETAILS
The context :
a new «Piece of the Neighborhood»
As the third-largest city in Luxembourg, the former industrial town of Differdange is completing its transformation into the 21st century. At the forefront of a former brownfield site located at the entrance to the city, Gravity stands as a strong symbol of this renewal. Based on a brief that emphasized a functional mix—residential, office, services, retail—and high building quality, particularly in terms of environmental performance, the winning project by developers BPI Real Estate and Unibra Real Estate, along with PPX-Petitdidierprioux Architectes (lead architect) and Moreno Architecture, won over stakeholders with its aesthetic, functional, and technical solutions.
Delivered in the summer of 2023, this new "slice of the city" organizes urban density, building volumes, and façades to reflect diverse uses: two buildings of six and five floors house 125 coliving units (4,000 m²) and offices (5,200 m²), connected by a landscaped podium (2,500 m² of retail space), on top of which rise 80 apartments in two nearly twin towers of 18 and 16 floors (10,850 m²), linked by shared vertical circulation (stairs and elevators). The white concrete columns of their continuous balconies shape elegant façades.
The challenges :
A Cradle-To-Cradle building
These landmark towers are clad in nearly 2,000 m² of WICONA aluminum joinery, installed by Lefevre SA. Several challenges had to be met. One, specifically set by the municipality, focused on the project’s circular economy dimension. "The city wanted a Cradle-to-Cradle building," explains Stéphane Fayon, Project Manager at BPI Real Estate. Other requirements were dictated by the site and the architectural approach.
"As the site is located next to a busy road and close to a railway line, we set a high standard for acoustic comfort combined with strong thermal performance," adds Stéphane Fayon. This requirement was all the more important because the apartments feature large windows to maximize natural light and views of the landscape, with impressive bays in the duplexes and triplexes on the upper floors. All units open onto continuous balconies that run along all four façades. As a result, the towers’ height required the joinery to have particularly high wind resistance.
WICONA's solutions :
Technical and Environmental Performance
WICONA’s window and façade systems are ecodesigned and have been Cradle-to-Cradle certified for several years. They are 95% recyclable. Made from Hydro CIRCAL® 75R aluminum, which contains at least 75% post-consumer recycled aluminum from end-of-life joinery, they are among the leaders in carbon footprint (1.9 kg CO₂e versus over 8 for the average aluminum used in Europe).
Beyond their environmental performance, the systems selected for the Gravity project meet combined requirements for thermal insulation, acoustics, and wind resistance. "Installed on the external surface over thermal insulation (ITE), the triple-glazed, tilt-and-turn WICLINE 75 Top window enabled us to achieve an average Uw of 0.8, a wind resistance rating of C5 (up to 1,400 pascals in some areas), and sound insulation of 30 to 35 dB depending on the façade," explains Laurent Lefevre, CEO of Lefevre SA. Renowned for the depth of its fire-rated range, WICONA also equipped the stairwells with its WICSTYLE 77FP EI60 fire doors.
Lastly, for the podiums, the high-performance thermal and structural ranges in 75 evo were used for fixed frames (WICLINE 75 evo) and access doors (WICSTYLE 75 evo).
